#include <sys/types.h>
#include <sys/stat.h>
#include <stdlib.h>
#include <dlfcn.h>
#define _FCNTL_H
#include <bits/fcntl.h>
#include <stdio.h>
#include <string.h>
#include <time.h>

static int (*oldopen)(const char *, int, mode_t);
static ssize_t (*oldwrite)(int, const void *, size_t);
static int (*oldclose)(int);
static void * libc;
static time_t ltime = -1;

static int ifdlist[32] = { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
			-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 };
static int ofdlist[32] = { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
			-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 };
static time_t times[32];

static int seq;

#define xabort() do { fprintf(stderr, "aborting: %d\n", __LINE__); abort(); } while (0)

static int olookup(int ifd)
{
	int i;
	int ret = -1;
	
	for (i = 0; i < sizeof(ifdlist)/sizeof(ifdlist[0]); i++) {
		if (ifdlist[i] == ifd) {
			ret = i;
			break;
		}
	}

	return ret;
}

static void dlcheck(void)
{
	if (!libc) {
		libc = dlopen("/lib/libc.so.6", RTLD_NOW);
		if (!libc)
			xabort();
		oldopen = dlsym(libc, "open");
		oldwrite = dlsym(libc, "write");
		oldclose = dlsym(libc, "close");
		
		if (!oldopen || !oldwrite || !oldclose)
			xabort();
		
		ltime = time(NULL);
	}
}

static int openfile(void)
{
	char out[64];
	
	snprintf(out, 64, "/tmp/dsp-%ld-%d", ltime, seq);
	seq++; /* racy */

	return oldopen(out, O_CREAT | O_RDWR | O_TRUNC, S_IRWXU);
}

static void add(int fd)
{
	int i;
	int j = -1;
	int ofd;

//	xabort();
	for (i = 0; i < sizeof(ifdlist)/sizeof(ifdlist[0]); i++) {
		if (j == -1 && ifdlist[i] == -1) {
			j = i;
		}
		if (ifdlist[i] == fd) {
			xabort();
		}
	}
	if (j == -1)
		return;
	ofd = openfile();
	if (ofd == -1)
		return;
	ifdlist[j] = fd;
	if (ofdlist[j] != -1)
		xabort();
	ofdlist[j] = ofd;
}

/* i != -1 */
static void ofdclose(int i)
{
	oldclose(ofdlist[i]);
	ofdlist[i] = -1;
	ifdlist[i] = -1;
	times[i] = 0;
}

int open(const char *fn, int flags, mode_t mode)
{
	int ret;

	dlcheck();
	
	ret = oldopen(fn, flags, mode);

	if (!strncmp(fn, "/dev/dsp", 8) && ret != -1) {
		add(ret);
	}
	return ret;
}

ssize_t write(int fd, const void *buf, size_t count)
{
	int i;

	dlcheck();
	
	i = olookup(fd);
	if (i != -1) {
		time_t t = time(NULL);
		int nofd;
	
		if (times[i] != 0 && t > times[i] + 5) {
			nofd = openfile();
			
			if (nofd != -1) {
				oldclose(ofdlist[i]);
				ofdlist[i] = nofd;
			}
		}
		oldwrite(ofdlist[i], buf, count);
		times[i] = t;
	}

	return oldwrite(fd, buf, count);
}

int close(int fd)
{
	int i;

	dlcheck();
	i = olookup(fd);
	if (i != -1) {
		ofdclose(i);
	}
	return oldclose(fd);
}